it is possible I have done it. However direct spray into the engine is not possible as you could never get the orifice small enough. even at .0001 diameter the volume is to large. the only way it was successful was to fog it in front of the intake and let the engine take what it wanted. Yes it is extremly hard on engine parts, yes I blew a few engines up, yes it was awesome when it worked, yes it requires that you add an additional 6 parts of fuel for one part nitrous. The plus part is the glow plug acts like a fuse if the mixture is to lean and instantly burns out saving the engine. all that said it can be done, it ain't easy, but its awesome when it works as long as the engine is still in one piece. It also requires some fairly heavy parts to contain and distribute the nitrous if you want to do it safely. The hardware will weigh at least a pound.
Just here to give the world grief.